MP,
I am by no means an expert, but have done some reserch into different hook styles for my employer.
As I understand it, the conventional style hooks (the ones with the tang sticking out) could be susceptible to load release if the wrong size/shape ring is used. Under unique circumstances the ring could get flipped over the tang and cause release. This is not just a possibility with Canam conventional hooks, but others as well.
The keeperless design has no tang for the ring to possibly get hooked on, so no inadvertent release. This appears to be the newer, improved design although it has what some may consider a drawback when it comes to hooking up the load. Instead of just slapping the ring on the hook the ground crew must insert the ring and then move it up to close the hook. It does not default to closed like the conventional design.
I'm not defending any particular design or brand. I just got the impression that you interpreted the description on the Canam website as admission of a known design flaw.